3D-Printed Weapons & the Consequences

At-home 3D printing is on the rise, and what was once just a lofty promise is now a reality. More and more hobbyists are acquiring affordable printers, such as the Makerbot Replicator 2 and the RapMan Universal 3D (single/dual head) printer, to manufacture just about everything from toys to working clocks.

Some hobbyists have used these printers for fast-prototyping items that are controversial -- or even deadly. It comes as no surprise that some would attempt to replicate weapons systems (or at least parts of them) in an effort to create a fully functional gun. It's not exactly clear who was the first to fabricate a firearm using a 3D printer, but one example that has garnered global attention is "Have Blue," who designed an AR-15 lower receiver (converted to fire .22 ammunition), using a CAD file in the SolidWorks file format that is openly available from CNC Gunsmithing.

Have Blue's 3D-printed converted AR-15.(Source: Defense Distributed)

After a few modifications to the original file, he set to work fabricating the receiver using around $30 of ABS filament fed through his Stratasys printer. After prototyping a small-scale model, he fabricated the full-size receiver and used it to fire 200 rounds without catastrophic failure. The proof of concept of manufacturing a 3D-printed weapon was a complete success. Now the door is open for others to try their hand at the home weapons manufacturing business.

A group of hobbyists (most of them college students) have banded together to form a company known as Defense Distributed to expand on the 3D-printed weapons systems and provide open-source software to anyone who wants it. Defense Distributed began its quest with the Wiki Weapon Project, which aims to provide all the necessary CAD software for manufacturing plastic firearms using any 3D printer. The group expanded on Have Blue's AR-15 to prove the concept of building weapons with a printer. However, instead of testing Have Blue's .22 conversion build, the group went ahead with an AR-15 conversion in 5.7x28FN, which has more firepower than a .22 but provides less pressure than the standard .223 round.

The group printed the lower receiver using Objet ABS-like filament piped through a Connex 3D printer. The printed rifle fired six shots before breaking. Apparently, the receiver's threads couldn't handle the pressure and snapped at the buffer-tube connection. The group is now looking for funding and a federal firearms license to get its project off the ground.

The problems with 3D-printed firearms aren't limited to catastrophic failure. (It takes only one bullet to kill.) There is also the issue of legality. No federal laws address manufacturing weapons with 3D printers, so anyone owning a printer could make a weapon -- even if they're not allowed to own one. The ATF considers the rifle's lower receiver as the firearm; anyone can purchase the upper receiver, barrel, etc.

The 1988 Undetectable Firearms Act prohibits the manufacturing or possession of guns that can't be picked up by airport metal detectors. This creates a loophole for hobbyists. Firearms typically require metal parts (barrel, springs, bolt, etc.) to function, and those parts can be detected. However, some companies don't want to take any chances. Defense Distributed's first attempt at funding in September through Indiegogo ended in disaster; Indiegogo froze DD's account and sent the $20,000 it raised back to the backers. In October, Stratasys terminated the group's 3D printer lease and seized the equipment from a member's home.

Like it or not, the seed of printing weapons has been planted, and the idea is sure to gain momentum through hobbyists in the near future -- until federal laws are enacted to gain control over the issue. It's only a matter of time before a printed weapon is used in a crime. Then all hell will break loose.

Wow, now that's a lot of attitude! I do feel sorry for those 250 engineers you know though. You could have ignored this of course, but no, you couldn't. You had to throw your 2 cents in to let everyone know just how right-wing you are, never to miss just such an opportunity. Besides, this is an issue for engineers to discuss just as was the nuclear bomb for physicists. Enjoy!

I'm rather dismayed to see the wrong fear-mongering question again being asked in one of our trade magazines. If we're going to write about 3D-printed guns, the question should be how to make new and innovative guns, not whether or not someone could make one for evil purposes. We can read about a new drug in terms of its benefits, without any mention of how someone could use it for criminal purposes. We can read about a new rocket motor without any mention of someone using it for a ballistic missile. We can read about a new metal alloy without worring that someone is going to use it to make a deadlier knife. And we can certainly read about all kinds of software innovations without any discussion of how someone could use them for criminal purposes. For that matter, people could (and sometimes do) use plain old 2D printers to commit fraud and forgery.

So how about Design News sending a reporter to a legitimate firearms company and interviewing the engineers there about how they are using 3D printers? I can think of two main applications. One is to produce non-firing prototypes to check fit and finish and fine-tune ease of assembly. The other is to produce PARTS for weapons in production. The AR15 platform seems to be the most popular for home builders.

Most of the receivier of any gun, but particularly an AR15, is subject to fairly low stress, and yet it has a complicated shape. In any gun, the chamber, the bolt, and the bolt lugs are the high-stress parts. Most of the rest is just a jig to hold the trigger assembly, stock, and magazine in position. A reasonable approach would be to machine or forge a piece of metal, of fairly simple shape, to carry the ~50,000 psi stresses of firing, while using 3D printed high-strength plastic to hold that and the other low-stress parts together.

An article focusing on how to optimally combine 3D printing with traditional metal manufacturing processes would also be far more useful to us real engineers than another round of hand-wringing about "what if criminals print guns?"

Everything, including new technologies, has unintended consequences. In light of our violent culture, it seems that discussing the ease of weapon manufacture is relevant just as is software development with regards to identity theft and that 2D printing technology you mentioned for counterfeiting. We can handle these seemingly peripheral topics as they are a consequence of the underlying technology.

Thanks for the article, it's a fun diversion to read the comments on these "red meat" subjects.

I would be interested in seeing the cost comparison between additive methods vs. other manufacture methods for the firearms industry. It would also be interesting to see how close state of the art 3D printing is to being a viable part of the industry and how close it is to being able to produce the stressed parts. Metal deposition is already being used in aerospace structural elements for fighter jets; but that customer base has deep pockets.

Wow... now someone feels sorry for me and my peers... I don't get it, but OK. The assumption that we "right-wing" types don't engage in broader discussion is just as inane as the assumption that the original article is worth the space it occupied on the cloud. Y'see... my friends and I are not about to lose one breath of sleep over the things that make the spineless jellyfish among the unarmed or otherwise defenseless populace squirm. Quite the opposite. As thinking men and women, as educated men and women, and as realistic men and women we routinely revel in the freedoms we claim as Americans and laud the creative application of all kinds of technology to the enjoyment and benefit of all. This is what engineering and design is all about. And, as the needle deflects from professional-level creativity to trade-level hands-on application, it is pure rubbish to ask that fine folks within our government protect us from ourselves. Quite honestly we are more than capable of doing so without much assistance, especially if we are not stripped of the freedom that allows us to do so. Attitude? Yes, absolutely. I am proud to be an American, proud to be as self-sufficient as I can be, and proud to live with little or no fear. How can one possibly live in this great land of ours without some "attitude"? But it's a good and wholesome attitude. I refuse to become part of the hysterical set that demands that EVERYONE stripped down to a cell phone and a home alarm system as self-defense mechanisms. Too slow, too ineffective, and too late. And, quite frankly... the attitude embodied in the original article is far more bothersome to freedom-loving Americans than ANY of its opposition so well-expressed by those who took the time to express their valuable counter-arguments. Enjoy?? indeed. Bring it. I LOVE a good debate.

I'm not sure selling a weapon you make is a problem. Unless the weapon leaves the state you live in. There are more than one groups of people who have thought of manufacturing weapons in Texas. There are some thinking of making 100 watt incandescent light bulbs. There is no problem till the articles cross the start line and come under Federal jurisdiction.

My thought was to use the printer to make prototypes for casting molds

I don't feel sorry for you but those you know. You didn't comprehend my post so of course you don't get it. What was that diatribe about? First you don't want to talk about the implications of the 3D printing of guns and then you spill your guts about what you believe, which is nothing but singing the praises of your "freedom" (whatever that means) loving, and more important, tough self. Wow! You're not afraid! Thanks for letting us know.

The fact is that guns don't guarantee "freedom" (whatever that means), culture does. This article is not a wate of time as it forces a discussion of things that are a consequence of engineering and are thus part of engineering. Of course you could "debate", but you haven't. All you've done is belly ache about you.

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